Screening of oxygen evolution electrocatalysts by scanning electrochemical microscopy using a shielded tip approach

Area of Science:

• Electrochemistry
• Materials Science
• Surface Science

Background:

• Developing efficient electrocatalysts for the oxygen evolution reaction (OER) is crucial for energy technologies.
• Screening catalyst libraries requires methods that can isolate and assess individual components within mixtures.
• Traditional methods struggle to differentiate the activity of adjacent electrocatalyst sites due to product diffusion.

Purpose of the Study:

• To develop and validate a scanning electrochemical microscopy (SECM) method for high-throughput screening of OER electrocatalysts.
• To accurately measure the activity of individual catalyst spots within combinatorial mixtures (Sn(1-x)Ir(x)O2).
• To demonstrate the effectiveness of a novel tip-shielding technique in mitigating interference from neighboring sites.

Main Methods:

• Utilized scanning electrochemical microscopy (SECM) in substrate generation-tip collection (SG-TC) mode.
• Prepared electrocatalyst arrays of pure IrO2 and Sn(1-x)Ir(x)O2 using a sol-gel route.
• Implemented a gold-shielded SECM tip, held at a constant potential, to selectively collect/consume reaction products.

Main Results:

• The shielded SECM tip successfully minimized interference from neighboring electrocatalyst spots.
• The SG-TC mode with the tip shield enabled accurate determination of individual spot activities in the catalyst array.
• Simulations and experimental data confirmed the efficacy of the tip shield for analyzing composite materials.

Conclusions:

• The developed SECM setup with a tip shield is highly effective for screening OER electrocatalyst libraries.
• This method allows for precise characterization of individual components in complex electrocatalytic materials.
• The approach facilitates accelerated discovery and optimization of advanced electrocatalysts for the oxygen evolution reaction.